U.S. patent number 7,589,245 [Application Number 11/179,459] was granted by the patent office on 2009-09-15 for process for preparing linear alpha olefins.
This patent grant is currently assigned to Shell Oil Company. Invention is credited to Eric Johannes Maria De Boer, Inge Oosterveld, Harry Van Der Heijden, Arie Van Zon.
United States Patent |
7,589,245 |
Maria De Boer , et
al. |
September 15, 2009 |
Process for preparing linear alpha olefins
Abstract
A process for the preparation of linear alpha olefins having 2n
carbon atoms from linear alpha olefins having n carbon atoms
comprising the steps of (a) dimerizing a linear alpha olefin having
n carbon atoms in the presence of a dimerization catalyst to
produce a linear internal olefin having 2n carbon atoms; (b)(i)
reacting the linear internal olefin having 2n carbon atoms produced
in step (a) with a trialkylaluminium compound in the presence of a
catalytic amount of an isomerization/displacement catalyst in order
to cause isomerization of the linear internal olefin and to
displace alkyl group(s) from said trialkylaluminium compound to
form an alkyl aluminium compound wherein at least one of the alkyl
groups bound to aluminium is a linear alkyl which has been derived
from the isomerization of said linear internal olefin; and (b)(ii)
reacting said alkyl aluminium compound with an alpha olefin
optionally in the presence of a displacement catalyst so as to
displace said linear alkyl from said alkyl aluminium compound to
form a linear alpha olefin having 2n carbon atoms.
Inventors: |
Maria De Boer; Eric Johannes
(Amsterdam, NL), Van Der Heijden; Harry (Amsterdam,
NL), Oosterveld; Inge (Amsterdam, NL), Van
Zon; Arie (Amsterdam, NL) |
Assignee: |
Shell Oil Company (Houston,
TX)
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Family
ID: |
35285245 |
Appl.
No.: |
11/179,459 |
Filed: |
July 12, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060014989 A1 |
Jan 19, 2006 |
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Foreign Application Priority Data
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Jul 13, 2004 [EP] |
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04254169 |
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Current U.S.
Class: |
585/328; 585/329;
585/510; 585/511 |
Current CPC
Class: |
C07C
1/327 (20130101); C07C 2/08 (20130101); C07C
5/2575 (20130101); C07C 1/327 (20130101); C07C
11/02 (20130101); C07C 2/08 (20130101); C07C
11/02 (20130101); C07C 5/2575 (20130101); C07C
11/02 (20130101); C07C 2523/755 (20130101); C07C
2527/128 (20130101); C07C 2531/14 (20130101) |
Current International
Class: |
C07C
2/26 (20060101); C07C 2/34 (20060101) |
Field of
Search: |
;585/328,329,510,511 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 505 834 |
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Mar 1992 |
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EP |
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1125928 |
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Aug 2001 |
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EP |
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1127987 |
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Aug 2001 |
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EP |
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418462 |
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Sep 1974 |
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SU |
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2004/037415 |
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May 2004 |
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WO |
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Other References
Britovsek G J P et al: "Iron-Catalyzed Polyethylene Chain Growth on
Zinx: Linear Alpha-Olefins with a Poisson Distribution" Angewandte
Chemie. International Edition, Wiley-VCH, Weinheim, DE, vol. 41,
No. 3, Jan. 29, 2002, pp. 484-491, XP002286464. cited by other
.
Gibson Vernon C et al: "The nature of the active species of
bis(imino) pyridyl cobalt ethylene polymerisation catalysts"
Chemical Communications Chemcom, Royal Society of Chemistry, GB,
No. 21, 2001, pp. 2252-2253, XP002196345 ISSN 1359-7345. cited by
other .
Small Brooke L. et al: "Iron-Based Catalysts with Exceptionally
High Activities and Selectivities for Oligomerizationof Ethylene to
Linear.Alpha-Olefins" Journal of the American Chemical Society,
Washington, DC, US, vol. 120, No. 28 Jul. 22, 1998, pp. 7143-7144,
XP002086898 ISSN:0002-7863. cited by other .
Ittel Steven D et al: "Late-Metal Catalysts for Ethylene Homo- and
Copolymerization" Chemical Reviews, American Chemical Society.
Easton, US, vol. 100, No. 4, 2000, pp. 1169-1203, XP000993140.
cited by other .
Britovsek G J P et al: "Oligomerisation of Ethylene by
Bis(imino)pyridyliron and -cobalt Complexes" Chemistry--a European
Journal, VCH Publishers, US vol. 6, No. 12, 2000, pp. 2221-2231,
XP000942739, ISSN 0947-6539. cited by other .
Britovsek G J P et al: "Novel olefin polymerization catalysts based
on iron and cobalt" Chemical Communications--Chemcom, Royal Society
of Chemistry, GB No. 7, 1998, pp. 849-850, XP002086893 ISSN
1359-7345. cited by other .
D. Vogt, Oligomerisation of Ethylene to Higher Alpha-Olefins in
Applied Homogeneous Catalysis with Organometallic Compounds, Ed. B.
Cornills, W.A. Hermann, 2nd Edition, vol. 1, Ch. 23.1.1, p.
240-253, Wiley-VCH 2002. cited by other .
D. van Leusen and B. Hessen, "1,1' Diisocyanoferrocene and a
Convenient Synthesis of Ferrocenylamine" Organometallics, 2001, 20,
pp. 224-226. cited by other .
Chemical Abstracts, vol. 134, Columbus, Ohio, US; Abstract No.
231149, Radecka-Paryzek, W. et al., "Metal-Ion-Directed Synthesis
of Homo- and Heteronuclear Dimetallic Schiff Base Podates," Polish
J. Chem. 2001, 75(1), pp. 35-42. cited by other .
T. Martijn Kooistra et al., Olefin Polymerizatino With
[{bis(imino)pyridyl}CO''Cl.sub.2]: Generation of the Active Species
Involves Co' Angewandte Chemie. International Edition, Wiley-VCH,
Weinheim, DE, vol. 40, No. 24, Dec. 17, 2001, pp. 4719-4722. cited
by other .
D. Vogt, "Oligomerization of Ethylene to Higher a-olefins" Ed. B.
Cornils, W.A. Hermann vol. 1, Ch. 2.3.1.3, p. 245-258, VCH 1996.
cited by other .
Lions, Francis et al. "Tridentate Chelate Compounds. I" J. Am.
Chem. Soc. (1957), vol. 79, 2733-38. cited by other .
Figgins, Paul et al., "Complexes of Iron(II), Co(II), and Ni(II)
with Biacetyl-bis-methylimine, 2-Pyridinal-methylimine and
2,6-Pyridinal-bis-methylimine," J. Am. Chem. Soc. (1960), vol. 82,
pp. 820-824. cited by other .
Brooke L. Small, "Tridentate Cobalt Catalysts for Linear
Dimerization and Isomerization of .alpha.-Olefins," Organometallics
2003, 22, pp. 3178-3183. cited by other .
Alison M. A. Bennett, "Novel, Highly Active Iron and Cobalt
Catalysts for Olefin Polymerization", Chemtech, Jul. 1999, vol. 29,
No. 7, pp. 24-28. cited by other .
Brooke L. Small and Maurice Brookhart, "Polymerization of Propylene
by a New Generation of Iron Catalysts: Mechanisms of Chain
Initiation, Propagation, and Termination," Macromolecules 1999,
vol. 32, No. 7, pp. 2120-2130. cited by other .
Daan van Leusen and Bart Hessen, "1,1'-Diisocyanoferrocene and a
Convenient Synthesis of Ferrocenylamine," Organometallics 2001, 20,
pp. 224-226. cited by other .
U.S. Appl. No. 11/088,023, filed Mar. 23, 2005, De Boer et al.
cited by other .
U.S. Appl. No. 11/080,170, filed Mar. 15, 2005, De Boer et al.
cited by other .
International Search Report for PCT/EP2005/053352 of Nov. 25, 2005.
cited by other .
Written Opinion for PCT/EP2005/053352 of Nov. 25, 2005. cited by
other.
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Primary Examiner: Dang; Thuan Dinh
Claims
The invention claimed is:
1. A process for the preparation of linear alpha olefins having 2n
carbon atoms from linear alpha olefins having n carbon atoms
comprising the steps of: (a) dimerizing a linear alpha olefin
having n carbon atoms in the presence of a dimerization catalyst
comprising (i) one or more transition metal complexes each
comprising a transition metal atom and a bis-arylimine pyridine
ligand and (ii) a co-catalyst compound to produce a linear internal
olefin having 2n carbon atoms; (b)(i) reacting the linear internal
olefin having 2n carbon atoms produced in step (a) with a
trialkylaluminium compound in the presence of a catalytic amount of
an isomerization/displacement catalyst in order to cause
isomerization of the linear internal olefin and to displace alkyl
group(s) from said trialkylaluminium compound to form an alkyl
aluminium compound wherein at least one of the alkyl groups bound
to aluminium is a linear alkyl which has been derived from the
isomerization of said linear internal olefin, and (b)(ii) reacting
said alkyl aluminium compound with an alpha olefin optionally in
the presence of a displacement catalyst so as to displace said
linear alkyl from said alkyl aluminium compound to form a linear
alpha olefin having 2n carbon atoms.
2. The process of claim 1 wherein n is an integer in the range of
from 3 to 11.
3. The process of claim 1 wherein the starting alpha olefin having
n carbon atoms comprises 1-butene and the linear alpha olefin
having 2n carbon atoms comprises 1-octene.
4. The process of claim 1 wherein said trialkyl aluminium compound
is selected from the group consisting of tri-n-hexylaluminium,
tri-isobutylaluminium, tri-n-butylaluminium, triethylaluminium,
tri-n-propylaluminium, tri-n-octylaluminium, tri-n-decylaluminium,
tri-n-dodecylaluminium, tri-n-tetradecylaluminium,
tri-n-hexadecylaluminium, tri-n-octadecylaluminium, and mixtures
thereof.
5. The process of claim 1 wherein the isomerization catalyst is a
nickel catalyst selected from the group consisting of nickel (II)
salts, nickel (II) carboxylates, nickel (II) acetonates and nickel
(0) complexes, and mixtures thereof.
6. The process of claim 1 wherein the bis-arylimine pyridine ligand
has the formula (I) below: ##STR00007## wherein R.sub.1-R.sub.5,
R.sub.7-R.sub.9, R.sub.12 and R.sub.14 are each, independently,
hydrogen, optionally substituted hydrocarbyl, an inert functional
group, or any two of R.sub.1-R.sub.3 and R.sub.7-R.sub.9 vicinal to
one another taken together may form a ring, and R.sub.6 is
hydrogen, optionally substituted hydrocarbyl, an inert functional
group, or taken together with R.sub.7 or R.sub.4 to form a ring,
R.sub.10 is hydrogen, optionally substituted hydrocarbyl, an inert
functional group, or taken together with R.sub.9 or R.sub.4 to form
a ring, R.sub.11 is hydrogen, optionally substituted hydrocarbyl,
an inert functional group, or taken together with R.sub.12 or
R.sub.5 to form a ring, R.sub.15 is hydrogen, optionally
substituted hydrocarbyl, an inert functional group, or taken
together with R.sub.14 or R.sub.5 to form a ring, provided that
R.sub.13 and at least one of R.sub.12 and R.sub.14 are
independently selected from optionally substituted C.sub.1-C.sub.30
alkyl, optionally substituted C.sub.4-C.sub.30 alkyloxy, halogen
and optionally substituted C.sub.5-C.sub.20 aryl, or R.sub.13 taken
together with R.sub.12 or R.sub.14 form a ring, or R.sub.12 taken
together with R.sub.11 form a ring and R.sub.14 taken together with
R.sub.15 form a ring, and provided that at least one of R.sub.12,
R.sub.13 and R.sub.14 is optionally substituted C.sub.4-C.sub.30
alkyloxy.
7. The process of claim 1 wherein the transition metal atom is
selected from Fe and Co.
8. The process of claim 1 wherein the co-catalyst compound is
selected from the group consisting of alkyl aluminiums,
aluminoxanes and mixtures thereof.
9. The process of claim 1 wherein the linear alpha olefin in step
(a) is the same as the alpha olefin in step (b)(ii).
10. The process of claim 9 wherein step (b)(ii) is performed with a
stoichiometric excess of alpha olefin over the amount required to
replace all the alkyl group(s) in said alkyl aluminium compound,
and step (b)(ii) leaves an olefin stream containing some unreacted
alpha olefin, at least part of which is reycled from step (b)(ii)
to step (a).
11. The process of claim 10 wherein the alpha olefin is 1-butene
said olefin stream comprises 2-butene, and at least some of the
2-butene in the stream is isomerized to 1-butene before use in step
(a).
12. The process of claim 9 wherein step (a) produces the linear
internal olefin of 2n carbons and leaves an olefin stream
comprising unreacted olefin of n carbon atoms, at least some of
said olefin stream being passed to step (b)(ii) as at least part of
the alpha olefin reacting with the alkyl aluminium compound.
13. The process of claim 12 wherein the alpha olefin is 1-butene,
said olefin stream comprises 2-butene, and at least some of the
2-butene in said stream is isomerized to 1-butene before passage of
at least some to step (b)(ii).
14. The process of of claim 11 wherein the isomerization is
performed with the isomerization/displacement catalyst of step
(b)(i).
15. A process for the preparation of a linear alpha olefin having
(n1+n2) carbon atoms comprising the steps of: (a) co-dimerizing a
linear alpha olefin having n1 carbon atoms with a linear alpha
olefin having n2 carbon atoms in the presence of a dimerization
catalyst comprising (i) one or more transition metal complexes each
comprising a transition metal atom and a bis-arylimine pyridine
ligand and (ii) a co-catalyst compound to produce a linear internal
olefin having (n1+n2) carbon atoms; (b)(i) reacting the linear
internal olefin having (n1+n2) carbon atoms produced in step (a)
with a trialkylaluminium compound in the presence of a catalytic
amount of an isomerization/displacement catalyst in order to cause
isomerization of the linear internal olefin and to displace alkyl
group(s) from said trialkylaluminium compound to form an alkyl
aluminium compound wherein at least one of the alkyl groups bound
to aluminium is a linear alkyl which has been derived from the
isomerization of said linear internal olefin having (n1+n2) carbon
atoms, and (b)(ii) reacting said alkyl aluminium compound with an
alpha olefin optionally in the presence of a displacement catalyst
so as to displace said linear alkyl from said alkyl aluminium
compound to form a linear alpha olefin having (n1+n2) carbon
atoms.
16. The process of claim 15 wherein n1 and n2 are each integers in
the range of from 3 to 11 and wherein n1 is a different integer
from n2.
17. The process of claim 15 wherein said trialkyl aluminium
compound is selected from the group consisting of
tri-n-hexylaluminium, tri-isobutylaluminium, tri-n-butylaluminium,
triethylaluminium, tri-n-propylaluminium, tri-n-octylaluminium,
tri-n-decylaluminium, tri-n-dodecylaluminium,
tri-n-tetradecylaluminium, tri-n-hexadecylaluminium,
tri-n-octadecylaluminium, and mixtures thereof.
18. The process of claim 15 wherein the isomerization catalyst is a
nickel catalyst selected from the group consisting of nickel (II)
salts, nickel (II) carboxylates, nickel (II) acetonates and nickel
(O) complexes, and mixtures thereof.
19. The process of claim 15 wherein the bis-arylimine pyridine
ligand has the formula (I) below: ##STR00008## wherein
R.sub.1-R.sub.5, R.sub.7-R.sub.9, R.sub.12 and R.sub.14 are each,
independently, hydrogen, optionally substituted hydrocarbyl, an
inert functional group, or any two of R.sub.1-R.sub.3 and
R.sub.7-R.sub.9 vicinal to one another taken together may form a
ring, and R.sub.6 is hydrogen, optionally substituted hydrocarbyl,
an inert functional group, or taken together with R.sub.7 or
R.sub.4 to form a ring, R.sub.10 is hydrogen, optionally
substituted hydrocarbyl, an inert functional group, or taken
together with R.sub.9 or R.sub.4 to form a ring, R.sub.11 is
hydrogen, optionally substituted hydrocarbyl, an inert functional
group, or taken together with R.sub.12 or R.sub.5 to form a ring,
R.sub.15 is hydrogen, optionally substituted hydrocarbyl, an inert
functional group, or taken together with R.sub.14 or R.sub.5 to
form a ring, provided that R.sub.13 and at least one of R.sub.12
and R.sub.14 are independently selected from optionally substituted
C.sub.1-C.sub.30 alkyl, optionally substituted C.sub.4-C.sub.30
alkyloxy, halogen and optionally substituted C.sub.5-C.sub.20 aryl,
or R.sub.13 taken together with R.sub.12 or R.sub.14 form a ring,
or R.sub.12 taken together with R.sub.11 form a ring and R.sub.14
taken together with R.sub.15 form a ring, and provided that at
least one of R.sub.12, R.sub.13 and R.sub.14 is optionally
substituted C.sub.4-C.sub.30 alkyloxy.
Description
FIELD OF THE INVENTION
The present invention relates to a process for preparing linear
alpha olefins including a dimerization reaction.
BACKGROUND OF THE INVENTION
Higher alpha olefins having 6 or more carbon atoms are important as
comonomers in polyolefins and as intermediates for detergent
compounds. For example, 1-hexene and 1-octene are used as
comonomers in LLDPE (linear low density polyethylene) and 1-decene
is used as a starting material for the production of synthetic
lubricants. However, there have hitherto only been general methods,
and not targeted syntheses, for preparing most of these higher
alpha olefins. These general methods tend to produce mixtures of
the desired higher alpha olefins with other olefinic products, e.g.
internal olefins. For example, the dehydrogenation of higher
paraffins leads to a mixture of olefins which mostly contain
internal double bonds. As another example, olefins having a
relatively high number of carbon atoms and terminal double bonds
can be prepared by the oligomerization of ethylene using transition
metal catalysts, for example, by the Ziegler process, the SHOP
process of Shell or the Ethyl Process. However, the mixtures
obtained have to be separated sometimes by very complicated methods
if a particular alpha olefin is to be isolated. In addition,
ethylene is a very expensive feedstock material which results in a
higher price for alpha olefins obtained by oligomerization.
For these reasons it would be desirable to provide a process for
producing alpha olefins in a targeted manner from starting
materials other than ethylene.
U.S. Pat. No. 5,124,465 and U.S. Pat. No. 5,191,145 disclose a
process for preparing linear higher alpha olefins by successive
transalkylation reactions. In these publications, a linear,
internal olefin having from 4 to 30 carbon atoms or a mixture of
such olefins is reacted with trialkylaluminium in the presence of
an isomerization catalyst. This results in the formation of a
trialkylaluminium compound in which at least one of the alkyl
radicals is derived from the olefin used. This radical is present
as a linear alkyl radical derived from the alpha olefins which has
been formed by isomerization. The trialkylaluminium compound is
subsequently reacted with an alpha-olefin in a displacement
reaction in which the linear alpha-olefin which was bound to the
aluminium is liberated. This process allows internal olefins to be
isomerised effectively and in good yields to produce terminal
olefins. However, the process is a pure isomerization reaction
which does not make it possible to increase the chain length. The
internal olefins used for the isomerization come from the usual
sources and a targeted synthesis of alpha olefins having a desired
chain length is not possible by means of the process.
U.S. 2004/0199035 and U.S. 2004/0054241 (BASF) relate to processes
for preparing higher alpha olefins by a combination of isomerising
transalkylation reactions with metathesis reactions. However, in
order to make 1-octene from transalkylation/metathesis methods, it
is necessary to start from 1-pentene. It would be desirable to
produce 1-octene from 1-butene since 1-butene (present in
Raffinate-II which is described below) is a relatively cheap and
abundant feedstock compared to 1-pentene.
It would be desirable to provide methods for producing higher alpha
olefins in a selective manner and, which, particularly for cost
reasons, makes use of feedstocks other than ethylene, particularly
relatively cheap feedstocks such as Raffinate (II) which contains a
mixture of 1-butene and 2-butene.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided
a process for the preparation of linear alpha olefins having 2n
carbon atoms from linear alpha olefins having n carbon atoms
comprising the steps of: (a) dimerizing a linear alpha olefin
having n carbon atoms in the presence of a dimerization catalyst to
produce a linear internal olefin having 2n carbon atoms; (b)(i)
reacting the linear internal olefin having 2n carbon atoms produced
in step (a) with a trialkylaluminium compound in the presence of a
catalytic amount of an isomerization/displacement catalyst in order
to cause isomerization of the linear internal olefin and to
displace alkyl group(s) from said trialkylaluminium compound to
form an alkyl aluminium compound wherein at least one of the alkyl
groups bound to aluminium is a linear alkyl which has been derived
from the isomerization of said linear internal olefin, and (b)(ii)
reacting said alkyl aluminium compound with an alpha olefin
optionally in the presence of a displacement catalyst so as to
displace said linear alkyl from said alkyl aluminium compound to
form a linear alpha olefin having 2n carbon atoms.
The process of the present invention advantageously produces linear
alpha olefins in high yield and selectivity in a targeted
manner.
DETAILED DESCRIPTION OF THE INVENTION
The process of the present invention comprises a dimerization
reaction (step (a)) and a transmerization reaction (steps b(i) and
b(ii)).
As used herein the term "transmerization" means a reaction which
comprises step (b)(i) and step (b)(ii) as defined herein. In
general terms, the term "transmerization" means a process that
combines isomerization and transalkylation steps and which produces
linear alpha olefins from linear internal olefins.
As used herein the term "dimerization" means a reaction by which an
olefin containing n carbon atoms is converted to an olefin
containing 2n carbon atoms.
The starting alpha olefin for use in the process of the present
invention may be any alpha olefin having n carbon atoms.
Preferably, n is an integer in the range from 3 to 11, more
preferably in the range from 4 to 6. The starting alpha olefin used
in the present process can be linear or branched. Preferably the
starting alpha olefin is linear. Examples of starting alpha olefins
which can be used in the present process are propene, 1-butene,
1-pentene and 1-hexene.
In a preferred embodiment herein the starting alpha olefin is
1-butene. When 1-butene is used as the starting alpha olefin,
1-octene is the alpha olefin produced by the process of the present
invention. Possible sources of 1-butene are olefin mixtures which
comprise 1-butene and 2-butene and possibly isobutene together with
butanes. These are obtained, for example, in various cracking
processes such as steam cracking or fluid catalytic cracking as C4
fraction. As an alternative, it is possible to use butene mixtures
as are obtained in the dehydrogenation of butanes, by dimerization
of ethene or in a Fischer-Tropsch reaction. Butanes present in the
C4 fraction behave as inerts. Dienes, alkynes or enynes present in
the mixtures can be removed by means of customary methods such as
extraction or selective hydrogenation.
Since olefin-containing C4 hydrocarbon mixtures are available at a
favourable price, the use of these mixtures improves the addition
of value to steam cracker by-products. Furthermore, products with
high added value are obtained.
The C4 fraction is most preferably used herein in the form of
raffinate II, with the C4 stream being freed of interfering
impurities, in particular oxygen compounds, by appropriate
treatment over guard beds, preferably over high surface area
aluminium oxides and/or molecular sieves. Raffinate II is obtained
from the C4 fraction by firstly extracting butadiene and/or
subjecting the stream to a selective hydrogenation. Removal of
isobutene then gives the raffinate II.
Another source of the starting alpha olefin is a mixture which has
been obtained by isomerizing the alpha olefin, such as a mixture of
alpha olefin and internal olefin of the same carbon skeleton, e.g.
1-butene and 2-butene. The content of alpha olefin e.g. 1-butene in
the isomerate may be increased by separation of at least some of
the internal olefin e.g. 2-butene, such as by distillation. Another
example of such a source, which may be equilibrium or non
equilibrium mixtures of alpha and corresponding internal olefins
e.g. 1-butene and 2-butene, is the unreacted linear olefin stream
from a catalytic dimerization, e.g. dimerization step (a)
optionally after isomerization and/or partial separation of
internal olefin (see below).
The alpha olefin reacted in dimerization step (a) may be the same
or different from the alpha olefin used as displacement alpha
olefin in back displacement step b(ii). Using different olefins for
the 2 steps can make separation of byproducts from one or both
reactions easier, as the byproducts from, e.g. reactions when
1-butene is used in step (a) and propene is used in step b(ii), are
of different carbon number and hence likely to be easier to
separate by distillation, than is likely to be the case when the
same olefin is used in both steps. However using the same olefin in
both steps has the advantage of simplicity of separation.
It is also envisaged that mixtures of linear alpha olefins can be
used as the starting olefin, including mixtures of odd and
even-numbered olefins (e.g. a mixture of 1-butene and 1-pentene).
Where the starting olefin is a mixture of olefins, some
co-dimerization can take place in addition to dimerization. For
example, in the case of a mixture of 1-butene and 1-pentene, the
reaction products could be a mixture of a linear internal octene
(from the dimerization of 1-butene), a linear internal decene (from
the dimerization of 1-pentene) and a linear internal nonene (from
the co-dimerization of 1-butene and 1-pentene).
Hence according to a further aspect of the present invention there
is provided a process for the preparation of a linear alpha olefin
having (n1+n2) carbon atoms comprising the steps of: (a)
co-dimerizing a linear alpha olefin having n1 carbon atoms with a
linear alpha olefin having n2 carbon atoms in the presence of a
dimerization catalyst to produce a linear internal olefin having
(n1+n2) carbon atoms; (b)(i) reacting the linear internal olefin
having (n1+n2) carbon atoms produced in step (a) with a
trialkylaluminium compound in the presence of a catalytic amount of
an isomerization/displacement catalyst in order to cause
isomerization of the linear internal olefin and to displace alkyl
group(s) from said trialkylaluminium compound to form an alkyl
aluminium compound wherein at least one of the alkyl groups bound
to aluminium is a linear alkyl which has been derived from the
isomerization of said linear internal olefin having (n1+n2) carbon
atoms, and (b)(ii) reacting said alkyl aluminium compound with an
alpha olefin optionally in the presence of a displacement catalyst
so as to displace said linear alkyl from said alkyl aluminium
compound to form a linear alpha olefin having (n1+n2) carbon
atoms.
Preferably, n1 and n2 are different and are each integers in the
range of from 3 to 11, more preferably in the range of from 4 to
6.
Dimerization
The process of the present invention comprises a dimerization step
(step (a)). In the dimerization step a linear alpha olefin having n
carbon atoms is dimerized in the presence of a dimerization
catalyst to produce a linear internal olefin having 2n carbon
atoms.
Alternatively, as mentioned above, the process of the present
invention comprises a co-dimerization step. The same process
conditions, dimerization catalysts and the like can be used for a
co-dimerization reaction as are described below for use in a
dimerization reaction.
Any suitable dimerization catalyst known to those skilled in the
art can be used in the process herein, provided it is highly
selective to the production of linear internal olefins. Preferred
dimerization catalysts for use herein are those which produce at
least 80%, preferably at least 90%, more preferably at least 95% of
linear internal olefins, such percentages being by weight of final
product produced from the dimerization of a starting linear alpha
olefin.
Suitable dimerization catalysts for use herein comprise transition
metal complexes based on a transition metal atom and a
bis-arylimine pyridine bidentate ligand, such as those disclosed in
Shell patent publications U.S. Pat. Nos. 6,710,006, 6,683,187, US
2005/0059786, US 2003/0119921 and co-pending U.S. patent
application Ser. No. 11/088,023, filed Mar. 23, 2005, the
disclosures of which are herein incorporated by reference in their
entirety. Other transition metal complexes suitable for use as
dimerization catalysts include those disclosed in U.S. Pat. No.
6,291,733 B1 (Chevron) which is herein incorporated by reference in
its entirety.
Other suitable dimerization catalysts for use herein include
titanium bisamide compounds such as those disclosed in US
2003/0045752 which is herein incorporated by reference in its
entirety.
Preferred catalyst compositions for use in the dimerization step
(a) of the present invention are those of the type disclosed in
co-pending U.S. patent application Ser. No. 11/088,023, filed Mar.
23, 2005, which is herein incorporated by reference in its
entirety. Such catalyst compositions comprise one or more
transition metal complexes, the transition metal complexes each
comprising a transition metal atom complexed with a bis-arylimine
pyridine ligand of formula (I) below:
##STR00001##
wherein R.sub.1-R.sub.5, R.sub.7-R.sub.9, R.sub.12 and R.sub.14 are
each, independently, hydrogen, optionally substituted hydrocarbyl,
an inert functional group, or any two of R.sub.1-R.sub.3 and
R.sub.7-R.sub.9 vicinal to one another taken together may form a
ring, R.sub.6 is hydrogen, optionally substituted hydrocarbyl, an
inert functional group, or taken together with R.sub.7 or R.sub.4
to form a ring, R.sub.10 is hydrogen, optionally substituted
hydrocarbyl, an inert functional group, or taken together with
R.sub.9 or R.sub.4 to form a ring, R.sub.11 is hydrogen, optionally
substituted hydrocarbyl, an inert functional group, or taken
together with R.sub.12 or R.sub.5 to form a ring, R.sub.15 is
hydrogen, optionally substituted hydrocarbyl, an inert functional
group, or taken together with R.sub.14 or R.sub.5 to form a ring,
provided that R.sub.13 and at least one of R.sub.12 and R.sub.14
are independently selected from optionally substituted
C.sub.1-C.sub.30 alkyl, optionally substituted C.sub.4-C.sub.30
alkyloxy, halogen and optionally substituted C.sub.5-C.sub.20 aryl
or R.sub.13 taken together with R.sub.12 or R.sub.14 form a ring,
or R.sub.12 taken together with R.sub.11 form a ring and R.sub.14
taken together with R.sub.15 form a ring. Preferably especially for
catalyst systems soluble in chemically inert non-polar solvents
(see further below) R.sub.13 and at least one of R.sub.12 and
R.sub.14 are independently selected from optionally substituted
C.sub.1-C.sub.30 alkyl, optionally substituted C.sub.4-C.sub.30
alkyloxy and optionally substituted C.sub.5-C.sub.20 aryl, provided
that at least one of R.sub.12, R.sub.13 and R.sub.14 is optionally
substituted C.sub.4-C.sub.30 alkyloxy.
One class of transition metal complexes suitable as catalyst
precursors for use in the dimerization step herein are
bis-arylimine pyridine MX.sub.n complexes which comprise a
bis-arylimine pyridine ligand of formula (I) above, wherein M is a
transition metal atom and n matches the formal oxidation state of
transition metal atom M and is preferably 1, 2 or 3; and X is
halide, optionally substituted hydrocarbyl (e.g. CH.sub.3,
neopentyl and CH.sub.2-Ph), C1-C6 alkoxide, amide, or hydride.
Particularly preferred X groups are halide, especially
chlorine.
Transition metals for use in the transition metal complexes herein
are preferably selected from any Group 4 to Group 10 transition
metal, more preferably Ti, V, Cr, Mn, Fe, Co, Ni, Pd, Rh, Ru, Mo,
Nb, Zr, Hf, Ta, W, Re, Os, Ir and Pt, even more preferably Ti, V,
Cr, Mn, Fe, Co, Ni, Pd and Pt, especially Fe, Co and Cr. The
preferred transition metal for use in the dimerization catalyst
herein is Co.
Bis-arylimine pyridine MX.sub.n complexes can be reacted with a
non-coordinating anion generating species to form a cationic
complex having the formula [bis-arylimine pyridine
MX.sub.p].sup.+[NC.sup.-].sub.p comprising a bis-arylimine pyridine
ligand having formula (I) above, wherein M and X are as defined
above, NC.sup.- is a non-coordinating anion; and p+q matches the
formal oxidation state of transition metal atom M. Preferably p+q
is 2 or 3.
By the term "non-coordinating anion" is meant an anion which does
not substantially coordinate to the metal atom M. Non-coordinating
anions (NC.sup.-) that may be suitably employed include bulky
anions such as tetrakis [3,5-bis(trifluoromethyl)phenyl]borate
(BAF.sup.-), (C.sub.6F.sub.5).sub.4B.sup.-, and anions of
alkylaluminium compounds including R.sub.3AlX'.sup.-,
R.sub.2AlClX'.sup.-, RAlCl.sub.2X'.sup.-, and "RAlOX'.sup.-",
wherein R is hydrogen, optionally substituted hydrocarbyl (e.g.
C1-C20 alkyl or aryl), or an inert functional group, and X' is
halide, especially chlorine or fluorine, C1-C20 alkoxide or
aryloxide (eg. phenoxide and substituted aryl oxides such as
2,4,6-trimethylphenyloxide, 2,4,6-tributylphenyloxide) or oxygen. A
preferred non-coordinating anion for use herein is tetrakis
[3,5-bis(trifluoromethyl)phenyl]borate (BAF.sup.-).
In a preferred embodiment of the invention, R.sub.13 and at least
one of R.sub.12 and R.sub.14 are independently selected from
optionally substituted C.sub.1-C.sub.30 alkyl, optionally
substituted C.sub.4-C.sub.30 alkyloxy, optionally substituted
C.sub.5-C.sub.20 aryl with the proviso that at least one of
R.sub.12, R.sub.13 and R.sub.14 is optionally substituted
C.sub.4-C.sub.30 alkyloxy.
In one class of bis-arylimine pyridine transition metal complexes,
the bis-arylimine pyridine ligand having formula (I) above, is such
that R.sub.8 and at least one of R.sub.7 and R.sub.9 are
independently selected from optionally substituted C.sub.1-C.sub.30
alkyl, optionally substituted C.sub.4-C.sub.30 alkyloxy, halogen
and optionally substituted C.sub.5-C.sub.20 aryl, or R.sub.8 taken
together with R.sub.7 or R.sub.9 form a ring, or R.sub.7 taken
together with R.sub.6 form a ring and R.sub.9 taken together with
R.sub.10 form a ring with the proviso that at least one of R.sub.7,
R.sub.8 and R.sub.9 is optionally substituted C.sub.4-C.sub.30
alkyloxy. Preferably R.sub.8 and at least one of R.sub.7 and
R.sub.9 are independently selected from optionally substituted
C.sub.4-C.sub.30 alkyl, optionally substituted C.sub.4-C.sub.30
alkyloxy and optionally substituted C.sub.5-C.sub.20 aryl.
It will be immediately apparent to the person skilled in the art,
that when R.sub.8 and at least one of R.sub.7 and R.sub.9 are
independently selected from optionally substituted C.sub.4-C.sub.30
alkyl, optionally substituted C.sub.4-C.sub.30 alkyloxy and
optionally substituted C.sub.5-C.sub.20 aryl with the proviso that
at least one of R.sub.7, R.sub.8 and R.sub.9 is optionally
substituted C.sub.4-C.sub.30 alkyloxy, it is not possible for
R.sub.8 to be independently, hydrogen, optionally substituted
hydrocarbyl, an inert functional group, or any two of
R.sub.7-R.sub.9 vicinal to one another taken together to form a
ring.
The term "Hydrocarbyl group" as used herein means a group
containing only carbon and hydrogen atoms. Unless otherwise stated,
the number of carbon atoms is preferably in the range from 1 to 30,
especially from 1 to 8. Unless otherwise stated, the hydrocarbyl
group may be saturated or unsaturated, aliphatic, cycloaliphatic or
cycloaromatic (e.g. phenyl), but is preferably aliphatic. Suitable
hydrocarbyl groups include primary, secondary and tertiary carbon
atom groups such as those described below.
The phrase "optionally substituted hydrocarbyl" as used herein is
used to describe hydrocarbyl groups which may optionally contain
one or more "inert" heteroatom-containing functional groups. By
"inert" it is meant that the functional groups do not interfere to
any substantial degree with the catalytic process in which the
transition metal complex may be employed. Non-limiting examples of
such inert groups are halides, such as fluoride and chloride,
silanes, stannanes, ethers, alkoxides and amines with adequate
steric shielding, all well-known to those skilled in the art. Some
examples of such groups include methoxy, trimethylsiloxy and
eicosanoxy. Said optionally substituted hydrocarbyl may include
primary, secondary and tertiary carbon atom groups of the nature
described below.
The term "inert functional group" as used herein means a group
other than optionally substituted hydrocarbyl which is inert under
the reaction conditions for any reaction or process in which the
transition metal complex may be employed. By "inert" it is meant
that the functional group does not interfere to any substantial
degree with the catalytic process in which the transition metal
complex may be employed. Examples of inert functional groups
suitable for use herein include halides, ethers, and amines such as
tertiary amines. Preferably the inert functional group is a halide,
especially fluorine and chlorine.
The term "Primary carbon atom group" as used herein means a
--CH.sub.2--R group wherein R is selected from hydrogen, an
optionally substituted hydrocarbyl (preferably selected from
C.sub.1-C.sub.6 alkyl, phenyl, and C.sub.1-C.sub.6 alkoxy or
aryloxy (e.g. OPh)), or an inert functional group (preferably
selected from fluorine, chlorine and --N(C.sub.1-C.sub.6
alkyl).sub.2). Examples of suitable primary carbon atom groups
include, but are not limited to, --CH.sub.3, --C.sub.2H.sub.5,
--CH.sub.2Cl, --CH.sub.2OCH.sub.3,
--CH.sub.2N(C.sub.2H.sub.5).sub.2, --CH.sub.2--C(CH.sub.3).sub.3,
--CH.sub.2--O-Ph and --CH.sub.2Ph. Unless otherwise stated,
preferred primary carbon atom groups for use herein are those
wherein R is selected from hydrogen or a C.sub.1-C.sub.6
unsubstituted hydrocarbyl, preferably wherein R is selected from
hydrogen, C.sub.1-C.sub.6 alkyl and phenyl, more preferably wherein
R is hydrogen or a C.sub.1-C.sub.3 alkyl.
The term "Secondary carbon atom group" as used herein means a
--CH(R).sub.2 group wherein each R is independently selected from
an optionally substituted hydrocarbyl (preferably selected from a
C.sub.1-C.sub.6 alkyl, C.sub.1-C.sub.6 alkoxy or aryloxy (eg. OPh)
and phenyl), or an inert functional group (preferably selected from
fluorine and chlorine). Alternatively, the two R groups may
together represent a double bond moiety, e.g. .dbd.CH.sub.2, or a
cycloalkyl group, e.g. cyclohexyl. Examples of secondary carbon
atom groups include, but are not limited to, --CH(CH.sub.3).sub.2,
--CHCl.sub.2, --CHPh.sub.2, --CH.dbd.CH.sub.2 and cyclohexyl.
Unless otherwise stated, preferred secondary carbon atom groups for
use herein are those in which R is a C.sub.1-C.sub.6 unsubstituted
hydrocarbyl preferably a C.sub.1-C.sub.6 alkyl, more preferably a
C.sub.1-C.sub.3 alkyl.
The term "Tertiary carbon atom group" as used herein means a
--C(R).sub.3 group wherein each R is independently selected from an
optionally substituted hydrocarbyl (preferably selected from
C.sub.1-C.sub.6 alkyl and C.sub.1-C.sub.6 alkoxy), or an inert
functional group (preferably selected from chlorine and fluorine).
Alternatively, the three R groups may together represent a triple
bond moiety, e.g. --C.ident.CPh, or a ring system containing
tertiary carbon atoms such as adamantyl derivatives. Examples of
tertiary carbon atom groups include, but are not limited to,
--C(CH.sub.3).sub.3, --CCl.sub.3, --C.ident.CPh, 1-Adamantyl and
--C(CH.sub.3).sub.2(OCH.sub.3). Unless otherwise stated, preferred
tertiary carbon atom groups for use herein are those wherein each R
is a C.sub.1-C.sub.6 unsubstituted hydrocarbyl group, preferably
wherein each R is a C.sub.1-C.sub.6 alkyl group, more preferably a
C.sub.1-C.sub.3 alkyl group, even more preferably wherein each R is
methyl. In the case wherein each R is a methyl group, the tertiary
carbon atom group is tert-butyl.
The rings which may be formed by any two of R.sub.1-R.sub.3 and
R.sub.7-R.sub.9 vicinal to one another taken together, R.sub.6
taken together with R.sub.7, R.sub.10 taken together with R.sub.9,
R.sub.11 taken together with R.sub.12 and R.sub.15 taken together
with R.sub.14, are preferably optionally substituted
C.sub.5-C.sub.20 cyclic hydrocarbyl groups, more preferably
optionally substituted C.sub.5-C.sub.20 cycloaliphatic or
polycycloaliphatic groups or optionally substituted
C.sub.5-C.sub.20 aromatic or polyaromatic groups, even more
preferably optionally substituted C.sub.5-C.sub.8 cycloaliphatic or
aromatic groups, especially a C.sub.6 cycloaliphatic or aromatic
groups, especially benzene. Suitable optional substituents are any
suitable substituents known to those skilled in the art, preferably
halide (e.g. F, Cl), C.sub.1-C.sub.6 alkoxy (e.g. OCH.sub.3) and
C.sub.1-C.sub.6 alkyl groups (e.g. --CH.sub.3, t-butyl).
The rings which may be formed by R.sub.13 taken together with
R.sub.12 or R.sub.14, and, where applicable, R.sub.8 taken together
with R.sub.7 or R.sub.9 are preferably optionally substituted
C.sub.5-C.sub.20 cyclic hydrocarbyl groups, more preferably
optionally substituted C.sub.5-C.sub.20 cycloaliphatic or
polycycloaliphatic groups or optionally substituted
C.sub.5-C.sub.20 aromatic or polyaromatic groups, even more
preferably optionally substituted C.sub.5-C.sub.10 cycloaliphatic
or aromatic groups, even more preferably optionally substituted
C.sub.5-C.sub.8 cycloaliphatic or aromatic groups, especially
C.sub.5 and C.sub.6 cycloaliphatic or aromatic groups, especially
benzene. Suitable optional substituents are any suitable
substituents known to those skilled in the art, preferably halide
(e.g. F, Cl), C.sub.1-C.sub.6 alkoxy (e.g. --OCH.sub.3) and
C.sub.1-C.sub.6 alkyl groups (e.g. --CH.sub.3, t-butyl).
The rings which may be formed by R.sub.6 taken together with
R.sub.4, R10 taken together with R.sub.4, R.sub.11 taken together
with R.sub.5 and R.sub.15 taken together with R.sub.5, are
preferably optionally substituted nitrogen-containing cyclic groups
containing from 4 to 20 carbon atoms and at least one nitrogen
atom, more preferably optionally substituted nitrogen-containing
cycloaliphatic groups containing from 4 to 20 carbon atoms atoms
and at least one nitrogen atom, even more preferably optionally
substituted nitrogen-containing cycloaliphatic groups containing 4
to 5 carbon atoms and at least one nitrogen atom. Suitable optional
substituents are any suitable substituents known to those skilled
in the art, preferably halide (e.g. F, Cl), C1-C6 alkoxy (e.g.
--OCH.sub.3) and C1-C6 alkyl groups (e.g. --CH.sub.3, t-butyl).
In preferred embodiments herein, none of the R1-R15 groups form
rings with each other. Hence in formula I above it is preferred
that R1-R12 and R14 are each independently selected from hydrogen,
optionally substituted hydrocarbyl groups such as the primary,
secondary and tertiary carbon atoms groups defined above and inert
functional groups such as halide; with the proviso that R.sub.13
and at least one of R.sub.12 and R.sub.14 are independently
selected from optionally substituted C.sub.1-C.sub.30 alkyl,
optionally substituted C.sub.4-C.sub.30 alkyloxy and optionally
substituted C.sub.5-C.sub.20 aryl and further provided that at
least one of R.sub.12, R.sub.13 and R.sub.14 is optionally
substituted C.sub.4-C.sub.30 alkyloxy.
The term "optionally substituted C.sub.1-C.sub.30 alkyl" in
relation to the R.sub.12, R.sub.13 and R.sub.14 groups, and, where
applicable, the R.sub.7, R.sub.8 and R.sub.9 groups of formula (I)
above means a C.sub.1 to C.sub.30 linear or branched alkyl group,
which may be substituted with one or more "inert" functional groups
known to those skilled in the art, in particular a halide,
preferably fluorine. Preferred optionally substituted alkyl groups
comprise from 3 to 25 carbon atoms, more preferably from 4 to 20
carbon atoms. Preferably, the alkyl group is an unsubstituted alkyl
group. Examples of suitable "optionally substituted
C.sub.1-C.sub.30 alkyl" include octadecyl, tetradecyl, dodecyl,
decyl, octyl, hexyl, pentyl, tert-butyl and iso-propyl, especially
tert-butyl and iso-propyl.
The term "optionally substituted C.sub.4-C.sub.30 alkyloxy" in
relation to the R.sub.12, R.sub.13 and R.sub.14 groups, and, where
applicable, the R.sub.7, R.sub.8 and R.sub.9 groups of formula (I)
above means a C.sub.4-C.sub.30 optionally substituted alkyl group
which is attached to an oxygen atom, the alkoxy group being
attached to the aryl group of the bis-aryl imine pyridine backbone
via the oxygen atom. Preferably, the optionally substituted
alkyloxy group comprises from 6 to 30 carbon atoms, more preferably
from 8 to 30 carbon atoms, and most preferably from 10 to 25 carbon
atoms. Preferably, the alkyloxy group is an unsubstituted alkyloxy
group. Examples of suitable "optionally substituted
C.sub.4-C.sub.30 alkyloxy" include eicosanoxy, octadecyloxy,
hexadecyloxy, tetradecyloxy, dodecyloxy, decyloxy, hexyloxy,
pentyloxy, butyloxy and tert-butyloxy, especially eicosanoxy,
dodecyloxy, pentyloxy and tert-butyloxy. A particularly preferred
optionally substituted C4-C30 alkyloxy group is eicosanoxy.
The term "optionally substituted C.sub.5-C.sub.20 aryl" in relation
to the R.sub.12, R.sub.13 and R.sub.14 groups, and, where
applicable, the R.sub.7, R.sub.8 and R.sub.9 groups of formula (I)
above means an aryl or heteroaryl group, comprising from 5 to 20
ring atoms and wherein one or more of the ring atoms can be
substituted with one or more substituents known to those skilled in
the art, preferably selected from optionally substituted
hydrocarbyl, preferably C.sub.1-C.sub.6 alkyl, preferably methyl,
and "inert" functional groups, such as halide. In a heteroaryl
group, one or more of the ring atoms is a heteroatom, such as
nitrogen, oxygen or sulfur, provided that the heteroatom is inert
with regard to the catalytic process in which the transition metal
complex is employed. Preferably the heteroaryl groups are aromatic,
fully substituted or the heteroatom is fully shielded from the
transition metal atom. Preferred heteroaryl groups are 1-pyrrolyl
groups. Preferably all of the ring atoms are carbon atoms.
Within the term "optionally substituted C.sub.5-C.sub.20 aryl" is
encompassed mono- and poly-aromatic groups. Preferred optionally
substituted C.sub.5-C.sub.20 aryl groups comprise from 5 to 10 ring
carbon atoms, more preferably 5 or 6 ring carbon atoms. Preferably,
the aryl groups are unsubstituted aryl groups, including 1-pyrrolyl
groups. Most preferred are optionally substituted phenyl groups,
especially phenyl.
In one class of transition metal complexes herein, R.sub.13 and at
least one of R.sub.12 and R.sub.14 are independently selected from
optionally substituted C.sub.4-C.sub.30 alkyl, optionally
substituted C.sub.4-C.sub.30 alkyloxy and optionally substituted
C.sub.5-C.sub.20 aryl, with the proviso that at least one of
R.sub.12, R.sub.13 and R.sub.14 is optionally substituted
C.sub.4-C.sub.30 alkyloxy, and R.sub.8 and at least one of R.sub.7
and R.sub.9 are independently selected from optionally substituted
C.sub.4-C.sub.30 alkyl, optionally substituted C.sub.4-C.sub.30
alkyloxy and optionally substituted C.sub.5-C.sub.20 aryl, with the
proviso that at least one of R.sub.7, R.sub.8 and R.sub.9 is
optionally substituted C.sub.4-C.sub.30 alkyloxy.
In another class of transition metal complexes herein, R.sub.12,
R.sub.13 and R.sub.14 are all independently selected from
optionally substituted C.sub.4-C.sub.30 alkyl, optionally
substituted C.sub.4-C.sub.30 alkyloxy and optionally substituted
C.sub.5-C.sub.20 aryl, with the proviso that at least one of
R.sub.12, R.sub.13 and R.sub.14 is optionally substituted
C.sub.4-C.sub.30 alkyloxy.
In another class of transition metal complexes herein, R.sub.12,
R.sub.13 and R.sub.14 are all independently selected from
optionally substituted C.sub.4-C.sub.30 alkyl, optionally
substituted C.sub.4-C.sub.30 alkyloxy and optionally substituted
C.sub.5-C.sub.20 aryl, with the proviso that at least one of
R.sub.12, R.sub.13 and R.sub.14 is optionally substituted
C.sub.4-C.sub.30 alkyloxy.
Preferred transition metal complexes for use in the dimerization
step of the present invention comprise ligands according to formula
(I), in which the following R groups appear: R.sub.1-R.sub.3 are
hydrogen; and/or R.sub.4 and R.sub.5 are methyl, hydrogen, benzyl
or phenyl, preferably methyl, phenyl or hydrogen, more preferably
methyl.
One preferred class of transition metal complexes comprises ligands
according to formula (I), in which the following R groups appear:
R.sub.12 and R.sub.14 are independently selected from
C.sub.1-C.sub.30 alkyl and C.sub.5-C.sub.20 aryl, preferably
C.sub.5-C.sub.20 aryl, more preferably phenyl; R.sub.13 is
C.sub.4-C.sub.30 alkyloxy, preferably C.sub.10-C.sub.25 alkyloxy,
more preferably eicosanoxy.
Another preferred class of transition metal complexes comprise
ligands according to formula (I), in which the following R groups
appear: R7, R9, R.sub.12 and R.sub.14 are independently selected
from C.sub.1-C.sub.30 alkyl and C.sub.5-C.sub.20 aryl, preferably
C.sub.5-C.sub.20 aryl, more preferably phenyl; R8 and R.sub.13 is
C.sub.4-C.sub.30 alkyloxy, preferably C.sub.10-C.sub.25 alkyloxy,
more preferably eicosanoxy.
Another preferred class of transition metal complexes comprise
ligands according to formula (I), in which the following R groups
appear: R.sub.12 and R.sub.14 are independently selected from
C.sub.1-C.sub.30 alkyl and C.sub.5-C.sub.20 aryl, preferably
C.sub.5-C.sub.20 aryl, more preferably phenyl; R.sub.13 is
C.sub.4-C.sub.30 alkyloxy, preferably C.sub.10-C.sub.25 alkyloxy,
more preferably eicosanoxy; R.sub.6 is a tertiary carbon atom
group, preferably tert-butyl, and preferably R7-R10, R11 and R15
are hydrogen.
Another preferred class of transition metal complexes comprise
ligands according to formula (I), in which the following R groups
appear: R.sub.12 and R.sub.14 are independently selected from
C.sub.1-C.sub.30 alkyl and C.sub.5-C.sub.20 aryl, preferably
C.sub.5-C.sub.20 aryl, more preferably phenyl; R.sub.13 is
C.sub.4-C.sub.30 alkyloxy, preferably C.sub.10-C.sub.25 alkyloxy,
more preferably eicosanoxy; R.sub.6 is selected from
C.sub.1-C.sub.30 alkyl, preferably C.sub.1-C.sub.10 alkyl, more
preferably C.sub.3-C.sub.6 alkyl, most preferably tert-butyl or
iso-propyl; R.sub.8 and R.sub.10 are hydrogen; and preferably
R.sub.7 and R.sub.9 are hydrogen.
Another preferred class of transition metal complexes comprise
ligands according to formula (I), in which the following R groups
appear: R.sub.12 and R.sub.14 are independently selected from
C.sub.1-C.sub.30 alkyl and C.sub.5-C.sub.20 aryl, preferably
C.sub.5-C.sub.20 aryl, more preferably phenyl; R.sub.13 is
C.sub.4-C.sub.30 alkyloxy, preferably C.sub.10-C.sub.25 alkyloxy,
more preferably eicosanoxy; R.sub.6, R.sub.8 and R.sub.10 are each
independently selected from a primary carbon atom group, preferably
C.sub.1-C.sub.6 alkyl, more preferably methyl, and preferably R7,
R9, R11 and R15 are hydrogen.
Another preferred class of transition metal complexes comprise
ligands according to formula (I), in which the following R groups
appear: R.sub.12 and R.sub.14 are independently selected from
C.sub.1-C.sub.30 alkyl and C.sub.5-C.sub.20 aryl, preferably
C.sub.5-C.sub.20 aryl, more preferably phenyl; R.sub.13 is
C.sub.4-C.sub.30 alkyloxy, preferably C.sub.10-C.sub.25 alkyloxy,
more preferably eicosanoxy; R.sub.6, R.sub.8 and R.sub.10 are
independently selected from C.sub.1-C.sub.30 alkyl, preferably
C.sub.1-C.sub.10 alkyl, more preferably C.sub.1-C.sub.6 alkyl, most
preferably methyl, ethyl, iso-propyl or tert-butyl; and preferably
R.sub.7 and R.sub.9 are hydrogen.
Another class of transition metal complexes comprise ligands
according to formula (I), in which the following R groups appear:
R.sub.7 and R.sub.9 are independently selected from
C.sub.1-C.sub.30 alkyl and C.sub.5-C.sub.20 aryl, preferably
C.sub.5-C.sub.20 aryl, more preferably phenyl; R.sub.8 is
C.sub.4-C.sub.30 alkyloxy, preferably C.sub.10-C.sub.25 alkyloxy,
more preferably eicosanoxy.
In a preferred embodiment, the transition metal complex comprises a
ligand according to formula (I), wherein R.sub.1-R.sub.3 are
hydrogen, R.sub.4 and R.sub.5 are methyl, R.sub.6, R.sub.8 and
R.sub.10 are methyl, R.sub.7, R.sub.9, R.sub.11 and R.sub.15 are
hydrogen, R.sub.12 and R.sub.14 are phenyl and R.sub.13 is
eicosanoxy.
In another preferred embodiment, the transition metal complex
comprises a ligand according to formula (I), wherein
R.sub.1-R.sub.3 are hydrogen, R.sub.4 and R.sub.5 are methyl,
R.sub.6, R.sub.10, R.sub.11 and R.sub.15 are hydrogen, R.sub.7,
R.sub.9, R.sub.12 and R.sub.14 are phenyl and R.sub.8 and R.sub.13
is eicosanoxy.
In another preferred embodiment, the transition metal complex
comprises a ligand according to formula (I), wherein
R.sub.1-R.sub.3 are hydrogen, R.sub.4 and R.sub.5 are methyl,
R.sub.6 is tert-butyl, R.sub.7, R.sub.8, R.sub.9, R.sub.10,
R.sub.11 and R.sub.15 are hydrogen, R.sub.12 and R.sub.14 are
phenyl and R.sub.13 is eicosanoxy.
In another preferred embodiment, the transition metal complex
comprises a ligand according to formula (I), wherein
R.sub.1-R.sub.3 are hydrogen, R.sub.4 and R.sub.5 are methyl,
R.sub.6, R.sub.9, R.sub.12 and R.sub.14 are hydrogen, R.sub.7 and
R.sub.14 are iso-propyl, R.sub.10 and R.sub.11 are methyl and
R.sub.8 and R.sub.13 is eicosanoxy.
The catalyst compositions for use in the dimerization step herein
also preferably comprise at least one co-catalyst compound (b). The
purpose of co-catalyst compound(s) is to form an activated catalyst
system. In the case when a bis-arylimine pyridine MX.sub.n complex
is present, the co-catalyst is selected from (1) a co-catalyst
compound capable of abstracting an anion and transferring an
optionally susbstituted hydrocarbyl or hydride group to the metal
atom, or (2) a co-catalyst compound capable of abstracting an anion
and a co-catalyst compound capable of transferring an optionally
substituted hydrocarbyl or hydride group to the transition metal
atom. In the case when a cationic [bis-arylimine pyridine
MX.sub.p.sup.+] [NC.sup.-].sub.q complex is present, the
co-catalyst compound is selected from a co-catalyst compound
capable of transferring an optionally substituted hydrocarbyl or
hydride group to the transition metal atom.
A co-catalyst compound capable of abstracting an anion (X.sup.-
group) and transferring an optionally substituted hydrocarbyl or
hydride group to the transition metal atom (M), preferably at a
temperature in the range of -100.degree. C. to +300.degree. C., is
selected from alkylaluminium compounds such as alkylaluminoxane and
alkylaluminium halides. Preferred compounds of this type are
methylaluminoxane (MAO) and modified methylaluminoxane (MMAO).
A co-catalyst compound capable of transferring an optionally
substituted hydrocarbyl or hydride group to the transition metal
atom (M), preferably at a temperature in the range of -100.degree.
C. to +300.degree. C., is selected from alkylaluminium compounds
such as alkyl aluminoxanes, alkyl lithium compounds, Grignards,
alkyl tin and alkyl zinc compounds, such as diethyl zinc. Preferred
compounds of this type are methylaluminoxane (MAO) and modified
methylaluminoxane (MMAO).
A co-catalyst compound capable of abstracting an anion (X.sup.-
group) from the transition metal atom (M), preferably at a
temperature in the range of -100.degree. C. to +300.degree. C., is
selected from strong neutral Lewis acids such as SbF.sub.5,
BF.sub.3 and Ar.sub.3B, wherein Ar is a strong electron-withdrawing
aryl group such as C.sub.6F.sub.5 or
3,5-(CF.sub.3).sub.2C.sub.6H.sub.3 or from salts with
non-coordinating anions (NC.sup.-) such as tetrakis
[3,5-bis(trifluoromethyl)-phenyl]borate (BAF.sup.-),
(C.sub.6F.sub.5).sub.4B.sup.-, and anions of alkylaluminium
compounds including R.sub.3AlX'.sup.-, R.sub.2AlClX'.sup.-,
RAlCl.sub.2X'.sup.-, and "RAlOX'.sup.-", wherein R is hydrogen,
optionally substituted hydrocarbyl or an inert functional group,
and X' is halide, alkoxide or oxygen. A preferred salt with a
non-coordinating anion for use herein is sodium tetrakis
[3,5-bis(trifluoromethyl)-phenyl]borate (Na.sup.+ BAF.sup.-).
Additional co-catalyst compounds (c), which may be used in addition
to the co-catalyst compound(s) listed above, include, but are not
necessarily limited to, neutral Lewis donor molecules.
The term "neutral Lewis donor molecule" as used in herein means a
compound which may suitably act as a Lewis base, such as ethers,
amines, sulphides and organic nitriles, for example, triethylamine
or 2,6-di-tert-butylpyridine.
The ligands and transition metal complexes described hereinabove
may be prepared using the chemical processes and equivalent
processes to those illustrated in the examples of the present
invention and any references therein, as well as the processes
known from U.S. Pat. Nos. 6,710,006, 6,683,187, US 2005/0059786, US
2003/0119921 and any references incorporated therein.
Catalyst systems based on the transition metal complexes described
herein may be formed by mixing together the transition metal
complex or a mixture of a transition metal salt and the appropriate
bis-arylimine pyridine ligand of formula (I), co-catalyst
compound(s) (b), and optionally one or more additional co-catalyst
compounds (c), in any order.
Conveniently, the preparation of catalyst systems based on
transition metal complexes described herein may be performed in the
presence of the dimerization reaction mixture or in the presence of
a chemically inert solvent which may be polar or non-polar.
Preferably, the catalyst system is prepared in the presence of the
reaction mixture or in the presence of a chemically inert non-polar
solvent, more preferably in the presence of a chemically inert
non-polar solvent.
The use of a chemically inert non-polar solvent in the preparation
of the catalyst system for the dimerization step especially to
provide a solution of that catalyst system may be desired for ease
of handling, storage and use of the catalyst system, in particular
for accurate dosing of the catalyst composition, especially during
continuously operated reaction processes. Catalyst systems
disclosed in the copending U.S. application Ser. No. 11/088,023,
filed Mar. 23, 2005 mentioned above with transition metal complexes
having ligands of formula I are especially preferred for use in
such solutions. Examples of suitable chemically inert non-polar
solvents include o-, m- or p-xylene, toluene, benzene, pentane,
isopentane, heptane, cyclohexane and isooctane, preferably the
solvent is toluene, isopentane, cyclohexane and isooctane,
especially toluene and isooctane.
In one embodiment, the catalyst system for the dimerization step is
formed by combining a solution of the transition metal complex
dissolved in a chemically inert non-polar solvent with a solution
of the co-catalyst compound(s) (b) and optionally additional
co-catalyst compound(s) (c) in a chemically inert non-polar
solvent. The combining of these two separate solutions may be
performed either in the presence or the absence of the reactant
composition.
Alternatively, the catalyst system for the dimerization is formed
by combining a solution comprising a mixture of a transition metal
salt and a bis-arylimine pyridine ligand of formula (I) dissolved
in a chemically inert non-polar solvent with a solution of the
co-catalyst compound(s) (b) and optionally additional co-catalyst
compound(s) (c) in a chemically inert non-polar solvent. The
combining of these two separate solutions may be performed either
in the presence or the absence of the reactant composition.
In another embodiment, the catalyst system is formed by combining a
solution of the transition metal bis-arylimine pyridine complex in
a chemically inert non-polar solvent, with the co-catalyst
compound(s) (b) and optionally additional co-catalyst compound(s)
(c), which are present in the reaction media.
Alternatively, the catalyst system is formed by combining a mixture
of a transition metal salt and a bis-arylimine pyridine ligand of
formula (I) in a chemically inert non-polar solvent, with the
co-catalyst compound(s) (b) and optionally additional co-catalyst
compound(s) (c) which are present in the reaction media.
In another embodiment, the catalyst system is prepared by combining
all the components of the catalyst system in a chemically inert
non-polar solvent.
In another embodiment, the catalyst system for the dimerization is
prepared by combining all the components of the catalyst system in
the reaction media.
The dimerization reaction of the present invention may be
conveniently carried out using the following conditions.
A quantity of the catalyst system is usually employed in the
dimerization reaction mixture so as to contain from 10.sup.-3 to
10.sup.-9 gram atom of transition metal atom M per mole of feed
olefin to be reacted.
The dimerization reaction may be most conveniently conducted over a
range of temperatures from -100.degree. C. to +200.degree. C.,
preferably in the range of from -50.degree. C. to 150.degree. C.,
more preferably in the range of from -10.degree. C. to 120.degree.
C., most preferably from 10.degree. C. to 100.degree. C.,
especially from 20.degree. C. to 90.degree. C.
The dimerization reaction may be conveniently carried out at a
pressure of 0.01 to 15 MPa (0.1 to 150 bar(a)), more preferably 0.1
to 10 MPa (1 to 100 bar(a)), and most preferably 0.1 to 5 MPa (1 to
50 bar(a)).
The optimum conditions of temperature and pressure used for a
particular catalyst system to maximise the yield of linear dimers,
and to minimise the competing reactions such as isomerization of
the feed olefin can be readily established by one skilled in the
art.
The dimerization reaction can be carried out in the gas phase or
liquid phase, or mixed gas-liquid phase, depending upon the
volatility of the feed olefin and product olefins.
The dimerization reaction may be carried out in the presence of an
inert solvent which may also be the carrier for the catalyst system
and/or feed olefin. Suitable solvents include alkanes, alkenes,
cycloalkanes, and aromatic hydrocarbons. For example, solvents that
may be suitably used in the process of the present invention
heptane, isooctane, cyclohexane, benzene, toluene, and xylene.
Reaction times of from 0.1 to 10 hours have been found to be
suitable, dependent on the activity of the catalyst. The reaction
is preferably carried out in the absence of air or moisture.
The dimerization reaction may be carried out in a conventional
fashion. It may be carried out in a stirred tank reactor, wherein
the feed olefin and catalyst system or catalyst precursors are
added continuously to a stirred tank and the feed olefin and
catalyst system are removed from the stirred tank with the product
olefin, which may then be separated, and optionally the unused feed
olefin and/or the catalyst system are recycled back to the stirred
tank.
Alternatively, the reaction may be carried out in a batch reactor,
wherein the catalyst system or the catalyst system precursors, and
feed olefin are charged to an autoclave, and after being reacted
for an appropriate time, product is separated from the reaction
mixture by conventional means, such as distillation.
The product of dimerization or co-dimerization comprises linear
olefin product(s) of 2n or n1+n2 carbon atoms, and unreacted feed
linear olefin of n, or n1 and n2, carbon atoms. The product may
also comprise by-products such as isomerized feed linear olefin
e.g. linear 2-olefin isomer. Thus the product of dimerizing
1-butene comprises linear octenes, unreacted 1-butene and
2-butene.
The product, after separation from catalyst e.g. by distillation,
may be used as such in the transmerization step without any other
purification at all. It may however be purified first e.g. by
distillation to remove at least some of any solvent or diluent from
the dimerization. Any such purification may be as well as, instead
of, or combined with, purification to remove e.g. by distillation
hydrocarbons of lower volatility than the linear olefin of 2n or
n1+n2 carbons; examples of such hydrocarbons are unreacted
olefin(s) and/or isomerized olefin. The mixture of unreacted linear
1-olefin or 1-olefins and isomerized 1-olefin or 1-olefins from the
dimerization is preferably recycled to the dimerization step for
reuse, preferably after having been (re-)isomerized over an
isomerization catalyst such as Na/K on alumina, especially at a
temperature of 50-200.degree. C. such as 100-150.degree. C.,
especially under superatmospheric pressure such as 0.1-2 MPa
preferably 0.5-1.5 M to generate the thermodynamic equilibrium
mixture of linear olefins when the content of the 1-olefin in the
recycle mixture is less than the equilibrium concentration, and
optionally after separation of some of the isomerized olefin, e.g.
by means of distillation.
Thus in a preferred process the olefinic compounds in the
dimerization reaction product are distilled from the catalyst
residue and separated into a more volatile hydrocarbon fraction
containing the unreacted feed and isomers, and the linear olefin
product(s) of 2n or n1+n2 carbon atoms, which may or may not be
further separated from solvent or diluent before passing to the
transmerization stage.
Transmerization
The process of the present invention also comprises a
transmerization step, which is carried out after the
dimerization/co-dimerization step.
Transmerization comprises a combination of step (b)(i) and step
(b)(ii) as follows: b(i) reacting the linear internal olefin having
2n carbon atoms produced in dimerization step (a) with a
trialkylaluminium compound in the presence of a catalytic amount of
an isomerization/displacement catalyst in order to cause
isomerization of the linear internal olefin and to displace alkyl
groups from said trialkylaluminium compound to form an alkyl
aluminium compound wherein at least one of the alkyl groups bound
to aluminium is a linear alkyl which has been derived from the
isomerization of said linear internal olefin, and (b)(ii) reacting
said alkyl aluminium compound with an alpha olefin optionally in
the presence of a displacement catalyst so as to displace said
linear alkyl from said alkyl aluminium compound to form a linear
alpha olefin having 2n carbon atoms.
While not wishing to be bound by theory, it is believed that the
reaction in step (b)(i) of the linear internal olefin having 2n
carbon atoms with a trialkylaluminium compound in the presence of
an isomerization/displacement catalyst causes isomerization of the
linear internal olefin to form at least some linear alpha olefin,
which linear alpha olefin displaces alkyl groups from said
trialkylaluminium compound to form an alkyl aluminium compound
wherein at least one of the alkyl groups bound to aluminium is a
linear alkyl derived from said linear alpha-olefin.
The linear internal olefin having 2n carbon atoms is preferably
reacted with the trialkylaluminium compound, in a molar ratio in
the range of from 1:1 to 50:1, preferably from 2:1 to 4:1.
Preferred catalysts for use in step (b)(i) are those catalysts
which catalyze both isomerization and displacement, hence the use
of the term "isomerization/displacement catalyst". The
isomerization/diplacement catalyst for use in step (b)(i) can be
any catalyst suitable for isomerizing an internal olefinic double
bond, but is preferably a nickel based isomerization/displacement
catalyst, such as those disclosed in U.S. Pat. Nos. 5,124,465 and
5,191,145, which are herein incorporated by reference in their
entirety. The isomerization/displacement catalyst used herein is
preferably selected from nickel (II) salts, nickel (II)
carboxylates, nickel (II) acetonates and nickel (O) complexes,
which may be stabilized by means of a trivalent phosphorus
ligand.
Examples of nickel (II) salts include nickel halides e.g. nickel
(II) chloride, nickel (II) bromide, nickel (II) iodide, and their
hydrates. Also useful are nickel (II) oxide and nickel (II)
hydroxide.
Examples of suitable nickel salts include carboxylates, carbamates,
alkoxides, thiolates, catecholates, oxalates, thiocarboxylates,
tropolates, phosphinates, acetylacetonates, iminoacetylacetonates,
bis-iminoacetylacetonates, the solubility of which can be tuned by
an appropriate choice of substituents, as well known to those
skilled in the art.
Preferred metal salts for use herein are the optionally substituted
acetylacetonates, or x, (x+2)-alkanedionates, where x is an intege
e.g. 2 to 6 such as 2,4-alkanedionates and 3,5-alkanedionates. When
the acetylacetonates are substituted, preferred substituents are
C.sub.1-C.sub.6 alkyl groups, especially methyl. Examples of
suitable acetylacetonates include 2,4-pentanedionates,
2,2,6,6-tetramethyl-3,5-heptanedionates. Other examples are aryl
substituted y, (y+2)-alkanedionates such as
1-phenyl-1,3-butanedionates and 1,3-diphenyl-1,3-propanedionates.
Preferred acetylacetonates for use herein are the
2,4-pentanedionates.
Examples of nickel (II) carboxylates include nickel acetate, nickel
2-ethylhexanoate, nickel octanoate and nickel naphthenate.
An example of nickel acetonates includes nickel (II)
acetylacetonate.
Examples of Ni(0) complex catalysts include Ni(CO).sub.4 and nickel
(0) olefin complexes such as nickel bis-1,5-cyclooctadiene
(Ni(COD).sub.2), Ni(C.sub.2H.sub.4).sub.3, Ni(norbornene).sub.3 and
nickel cyclododecatriene.
A particularly preferred isomerization/displacement catalyst for
use in step (b)(i) is nickel bis-1,5-cyclooctadiene
(Ni(COD).sub.2).
Separate catalysts can be used for the isomerization and the
displacement provided that they do not interfere with each other.
Examples of displacement catalysts include, for example, colloidal
Ni, Pt, Co, nickel acetylacetonate, cobalt carboxylates, e.g.
cobalt naphthenate or cobalt acetate, nickel carboxylates, e.g.
nickel naphthenate and the like.
The trialkylaluminium compounds suitable for use in the process of
the present invention are known to those skilled in the art.
Preferably, the alkyl groups of the trialkylaluminium compounds
contain fewer carbons than the predominant carbon number of 2n of
the internal olefins. Suitable alkyl aluminium compounds which
contain alkyl groups having from 2 to 24 or 2-18 carbon atoms,
preferably from 2 to 12 carbon atoms, include, for example,
triethylaluminium, tri-n-propylaluminium, tri-n-butylaluminium,
tri-isobutylaluminium, tri-n-hexylaluminium, tri-n-octylaluminium,
tri-n-decylaluminium, tri-n-dodecylaluminium,
tri-n-tetradecylaluminium, tri-n-hexadecylaluminium,
tri-n-octadecylaluminium, and the like. A particularly preferred
trialkyl aluminium compound for use in step (b)(i) is
tri-n-propylaluminium.
According to isomerization/displacement step (b)(i), the
isomerization/displacement catalyst can be added to a mixture of
trialkyl aluminium and internal olefin. Alternatively, the catalyst
can be first mixed with the internal olefin(s) and this mixture can
be added to the trialkylaluminium. Both isomerization and
displacement can be simultaneously carried out in the same vessel.
Alternatively, the isomerization reaction can be initiated in a
first reactor and then fed to a second reactor containing the
trialkylaluminium. The reaction can be carried out in a batch or
continuous manner.
In order to favour the replacement of the alkyl groups by the
isomerized internal olefins, the displaced alkyl groups in the form
of their corresponding 1-olefins can be removed as vapour from the
reaction mixture and can be used in the recovery of isomerized
1-olefins by back-displacement. Unreacted internal olefins can be
separated from the reaction mixture using conventional methods such
as by distillation or vacuum stripping and can be recycled to the
isomerization/displacement step (b)(i).
Suitable reaction temperatures for the isomerization/displacement
step are in the range of from -20.degree. C. to 200.degree. C.,
preferably from 30.degree. C. to 100.degree. C. Suitable reaction
pressures range from 0-0.689 MPa (0 to 100 psia), preferably
0.0069-0.31 Mpa (1 to 45 psia) and reaction times usually range
from 0.1 to 2 hours.
Solvents are not necessary for the isomerization/displacement
reaction but can be used if desirable. Suitable solvents include
inert aliphatic and aromatic hydrocarbons.
It is sometimes advantageous, especially when using a reactor in
which distillation is also taking place, to include an inert
diluent such as isoheptane, heptane, octane, or isooctane in the
feed.
Thus in a preferred process, the isomerization/displacement stage
is performed in the presence of a solvent or diluent at least some
of which remains with the organo-aluminium product at the end of
the reaction. The reaction can be encouraged to go to completion by
distillation of the olefin displaced from the trialkyl aluminium
added to step (b)(i) to leave a solution or suspension of the
product organo-aluminium product together with catalyst.
This solution or suspension can be used as such in the back
displacement step (b)(ii) without purification, or may be treated
to separate the catalyst first especially if it is insoluble,
before the organo-aluminium product is used in step (b) (ii).
Step (b)(ii) is a displacement reaction wherein the alkyl groups
from the isomerized internal olefins are back-displaced from the
trialkyl aluminium compounds formed in the
isomerization/displacement reaction, by reaction of the trialkyl
aluminium compounds with a suitable alpha olefin. The displaced
1-olefin recovered from the isomerization/displacement reaction as
described above can be used as the alpha olefin to back-displace
the linear 1-olefin from the aluminium alkyl. The regenerated
trialkyl aluminium can then be recycled back to the
isomerization/displacement reaction. Alternatively, a different
olefin can be used for displacement step (b)(ii). Alpha olefins
having from 2 to 18 carbon atoms e.g. of 3-7 carbon atoms, and
mixtures of such olefins are suitable for use in displacement step
(b)(ii); mixtures comprising such an olefin, such as 1-butene, and
its internal olefin isomer such as 2-butene, or Raffinate II may be
used in step (b)(ii). A particularly preferred alpha olefin for use
in displacement step (b)(ii) is propene.
The amount of alpha olefin used in the displacement reaction should
be in stoichiometric excess over the amount required to replace all
alkyl groups, preferably at least a 200% excess, such as a
200-3000% excess.
The alpha olefin used for displacement in step b(ii) may be fresh
olefin or a mixture thereof with displaced 1-olefin from step b(i).
The displacing alpha olefin may comprise an equilibrium or non
equilibrium mixture of 1-olefin and at least one internal isomer
thereof having the same carbon skeleton; examples of such mixtures
are mixtures of 1-butene and 2-butene, preferably those produced as
a result of isomerization, optionally after removal of some
internal olefin such as 2-butene e.g. by distillation. The alpha
olefin used for displacement may also comprise excess of olefin
unreacted in step b(ii) and recycled. Thus preferably the
displacement olefin is a mixture of olefin displaced from step b(i)
and olefin unreacted from step b(ii). When the displacing olefin is
isomerizable under the reaction conditions of step (b) (ii), the
unreacted olefin stream from step b(ii) may also comprise
isomerized olefin such as internal olefin, e.g. 2-butene when
1-butene is the displacing olefin. The content of isomer in the
unreacted stream can be reduced by back isomerization, over an
isomerization catalyst and under conditions such as those described
above for isomerizing the mixture of linear 1 olefin and isomerized
1-olefin leaving from the dimerization.
Displacement step (ii) can be carried out in the absence of a
catalyst, but is preferably carried out in the presence of a
suitable amount of a displacement catalyst. Preferred displacement
catalysts are those which do not have any significant isomerization
activity under the conditions used. Examples of suitable
displacement catalysts include, for example, cobalt carboxylates
such as cobalt naphthenate and the like. Nickel complexes such as
nickel acetylacetonate, nickel carboxylates such as nickel
naphthenate and nickel acetate can be used if combined with lead or
other suitable materials to prevent isomerization.
The displacement reaction (b)(ii) is suitably carried out at a
reaction temperature of from -10.degree. C. to 200.degree. C., such
as 0 to 100.degree. C. and especially 0 to 50.degree. C. Step b(ii)
may be performed at a temperature about the same as step b(i) e.g.
plus or minus 10.degree. C., but preferably step b(ii) is at a
lower temperature such as 30-80.degree. C. lower. If the
displacement reaction is carried out in the absence of a catalyst
higher temperatures may be required.
The displacement reaction is generally carried out over a period of
from 30 seconds to 1 hour (at 25.degree. C.), preferably from 1
minute to 20 minutes.
The back displacement process liberates a linear alpha olefin
derived from the linear internal olefin fed to the
isomerization/displacement stage (b)(i) and produces a trialkyl
aluminium based on the displacing olefin added to stage (b)(ii).
The reaction product mixture from step (b)(ii) also usually
contains back displacement catalyst and often unreacted back
displacement olefin. It may contain some residual catalyst from
stage (b)(i). In addition, in particular when using a nickel based
displacement catalyst, it may have been desirable to have added a
poison such as a lead or copper poison or a cyclic olefin e.g.
cyclooctadiene in order to stop stage (b)(ii) when the back
displacement is substantially complete and before too much side
reaction has taken place. Under these circumstances such a poison
has to be separated if the trialkyl aluminium is to be recycled to
step (b)(i). The metals may be separated by filtration and the
cyclic olefin may be separated by distillation. Thus preferably at
the end of step (b)(ii) the product reaction mixture contains the
product alpha olefin, unreacted displacement olefin,
organoaluminium compound and possibly but preferably
solvent/diluent, and/or displacement catalyst and isomerization
catalyst, which had been carried over from step (b)(i) and
optionally poison. Distillation of the reaction mixture can
separate the product olefin and any residual unreacted displacement
olefin and optionally at least some of the solvent/diluent from the
remainder. After removal from the remainder of any poison and
catalysts, e.g. by filtration or distillation the organoaluminium
compound can then be recycled to step (b)(i). The used nickel
isomerization catalyst from step (b)(i) may have reduced
isomerization activity but enough displacement activity for step
(b)(ii) so extra displacement catalyst and optionally poison may
not necessarily be needed. Thus advantageously the nickel catalyst
and an organo aluminium compound may be used in step (b)(i) and
then for step (b)(ii) and then back in step b(ii), the nature of
the organo aluminium compound present oscillating between the two
steps. The steps (b) (i) and (b) (ii) may be performed in the same
reactor or two reactors in series. Unreacted displacement olefin
from step b(ii) can be recycled for reuse in that step b(ii).
Thus in a preferred process, 1-butene is dimerized over a
dimerization catalyst to form a mixture comprising 2-octene and
3-octene, together with more volatile components comprising
1-butene and 2-butene, and catalyst. The volatile components are
separated by distillation, passed to an isomerization stage, where
the 2-butene is back isomerized at least partly to 1-butene,
preferably with an isomerization catalyst such as Na/K on alumina,
especially at a temperature of 50-200.degree. C. such as
100-150.degree. C. and under superatmospheric pressure such as
0.11-2 MPa preferably 0.5-1.5 MPa; 1-butene may if desired then be
recovered from the isomerate and recycled for reuse in the
dimerization stage. The mixture comprising 2+3-octenes is separated
from the dimerization catalyst e.g. by distillation and then passed
to step b(i) where it is mixed with tripropyl aluminium and an
isomerization/displacement catalyst, such as a Ni compound, to
produce an organo aluminium which is an octyl or octyl propyl
aluminium and to displace propene which is usually distilled off
during the reaction. After the reaction unreacted 2+3-octenes can
be separated by distillation from the organo aluminium which is
then used in step b(ii). At least a molar excess of propene,
comprising displaced propene from step b(i) and unreacted recyled
propene from step b(ii), is then reacted in step b(ii) with the
organo aluminium usually in the presence of displacement catalyst
to form tripropylaluminium and liberate 1-octene. The 1-octene can
be separated by distillation from the excess of propene and any by
products such as hexenes. The residue from the 1-octene separation,
may be purified by separation of displacement catalyst, if any, and
then recycled to step b(i).
An appropriate transalkylation process carried out under
isomerizing conditions for use herein is described in U.S. Pat.
Nos. 5,124,465 and 5,191,145, which are herein incorporated by
reference in their entirety. The context of these applications is
an integral part of the present invention and is incorporated
herein by reference.
The overall process of the present invention may also
advantageously be performed with recycle of by product or unreacted
olefin streams from one of steps (a) and (b) for use as feed olefin
streams for the other step. The integrated process may be performed
in a batch, semi batch or preferably continuous manner. The
integrated process is performed in particular when the linear alpha
olefin is the same in step (a) and b (ii), especially when it is
propene and most especially when it is 1-butene.
In a first integrated process, step (b) (ii) is performed with a
stoichiometric excess of alpha olefin over the amount required to
replace all the alkyl group(s) in said alkyl aluminium compound,
and step (b)(ii) leaves an olefin stream containing some unreacted
alpha olefin, at least part of which is recycled from step (b)(ii)
to step (a). This recycle may be as well as recycle to step (a) of
at least some of unreacted alpha olefin which has been separated
from dimer product and/or dimerization catalyst at the end of step
(a). The recycle olefin streams may separately pass into the
dimerization step (a), but are advantageously mixed before entering
that step, usually with some fresh linear alpha olefin.
When the linear alpha olefin is propylene, the recycling may be
performed without any purification, except possibly from
oligomers.
When the linear olefin is 1-butene or other isomerizable olefin
such as 1-pentene or 1-hexene, the unreacted olefin stream from
step b(ii) may contain corresponding internal olefin isomer, such
as 2-butene. At least some of the stream may be recycled to step
(a) as such or after isomerization of at least some of the 2-butene
or other internal olefin isomer e.g. as described before in
relation to work up of olefin from steps (a) or (b)(ii); separation
of at least some of the isomer e.g. by distillation or otherwise
may also be performed before or after the isomerization. The
mixture of alpha and internal olefin isomers from step (b)(ii) may
be isomerized separately from any isomerization of the linear
olefin from step (a) and the products, if desired after separation
of internal isomer, passed separately to step (a); advantageously
the olefin streams from steps (a) and (b)(ii) are recycled together
to the isomerization from whence only one purified olefin stream
passes to step (a). The recycled olefin stream passed to step (a)
can be an equilibrium or non equilibrium mixture of alpha and
internal olefins.
In a second integrated process, step (a) produces linear internal
olefin of 2n carbon atoms and leaves one olefin stream comprising
unreacted olefin of n carbon atoms, which are separated and at
least some of the latter is passed to step b(ii) for use as at
least part of the displacing alpha olefin. This recycle may be as
well as recycle to step (b)(ii) of by-product/unreacted olefin from
step (b)(ii) and also passage of olefin-1 displaced from step
(b)(i) to (b)(ii). In the case of 1-butene or other isomerizable
alpha olefin, the unreacted olefin stream from step (a) may also
comprise 2-butene or other internal isomer and may be purified to
reduce its isomer content, in a manner as described above, such as
by isomerization and/or separation before passage of at least some
of said purified stream to step (b)(ii).
In a third integrated process, some of the by-product/unreacted
olefin from step (a) is passed, if desired after purification as
described, to step (a) and some to step (b)(ii). In an extension of
this type of process, by-product/unreacted olefin from step (b)(ii)
meets by product olefin from step (a) before passage, if desired
via purification as described, to both step (a) and step
(b)(ii).
A fourth aspect of an integrated process can be applied to
1-butene, or other isomerizable alpha olefin, as both feed olefin
for step (a) and displacement olefin for step (b)(ii). This process
is a modification of the first to third types of integrated process
in which the olefin mixture of linear alpha olefin and its isomer
from step (a) and/or step (b)(ii) is isomerized with the
isomerization/displacement catalyst of step (b)(i), usually in the
isomerization part of step (b)(i). The olefin mixture can be
isomerized over the isomerization catalyst used in that
transmerization in the presence or absence of the
trialkylaluminium. The olefin mixture may be passed concurrently
with the olefin dimer over the isomerization/displacement catalyst
in step (b)(i). Preferably the olefin mixture and olefin dimer are
passed alternately over the isomerization/displacement catalyst.
The olefin mixture may be passed over a first portion of
isomerization/displacement catalyst in a first reactor while the
olefin dimer is passed over a second portion of
isomerization/displacement catalyst in a second reactor; the first
and second reactors may be in parallel. This approach may allow
optimization of conditions for each reactor. The operation in
parallel also allows continuous isomerization of the olefin mixture
in the first reactor while the transmerization is performed semi
continuously in the second reactor e.g. with periodic removal of
solvent and/or catalyst and/or alkyl aluminium. Conditions of the
isomerization over the step (b)(i) catalyst may be as described
above for the transmerization step (b)(i) but are preferably under
superatmospheric pressure such as 0.11-2 MPa, preferably 0.5-1.5
MPa.
The isomerate produced in the fourth aspect of an integrated
process may be recycled, if desired after purification as
described, to at least one of steps (a) and (b)(ii).
The invention will now be illustrated by the following non-limiting
examples.
EXAMPLES
The example below demonstrates the conversion of 1-butene into
linear 1-octene using the process of the present invention.
General Procedures and Characterisation
All chemicals used in preparations were purchased from Aldrich and
used without further purification unless mentioned otherwise.
All the operations with the catalyst systems were carried out under
nitrogen atmosphere. All solvents used were dried using standard
procedures.
Anhydrous o-xylene (>97% purity) was stored over Na-wire and 4
.ANG. molecular sieves (final water content of about 3 ppm).
1-butene (grade 2.0, i.e. 99.0% purity) were purchased from Hoek
Loos N.V., Dieren, The Netherlands and was used without further
purification.
The products obtained were characterised by Gas Chromatography
(GC), in order to evaluate yield of C4, C8 and C12 compounds using
a HP 5890 series II apparatus and the following chromatographic
conditions:
Column: HP-1 (cross-linked methyl siloxane), film thickness=0.25
.mu.m, internal diameter=0.25 mm, length 60 m (by Hewlett Packard);
injection temperature: 325.degree. C.; detection temperature:
325.degree. C.; initial temperature: 40.degree. C. for 10 minutes;
temperature programme rate: 10.0.degree. C./minute; final
temperature: 325.degree. C. for 41.5 minutes; internal standard:
o-xylene or hexadecane.
The NMR data was obtained at room-temperature with a Varian 300 MHz
or 400 MHz apparatus.
Transition Metal Complex and Catalyst Preparation
The transition metal catalyst composition used in the dimerization
experiments below was a solution in xylene of
2-[1-(2-t-butylphenylimino)ethyl]-6-[1-(4-eicosanoxy-3,5-diphenylphenylim-
ino)ethyl]pyridine cobalt[II] chloride (B) and sodium
tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (a cationic catalyst
solution). The preparation of this catalyst composition, including
various starting materials, is described below.
Preparation of 4-hydroxy-3,5-diphenylacetanilide
##STR00002##
To 4-hydroxy-3,5-diphenylaniline (4 g, 15.3 mmol) in 30 ml of
ethanol was added 1.6 ml of acetic anhydride. The reaction was
stirred for 16 hours. The resulting mixture was poured into water.
The pink product (6 g) was isolated by filtration, washed with
water, dried and used without further purification.
.sup.1H-NMR (CDCl.sub.3, selected data) .delta. 5.31(s, OH), 2.16
(s, Me).
Preparation of 4-eicosanoxy-3,5-diphenylacetanilide
##STR00003##
A mixture of 4-hydroxy-3,5-diphenylacetanilide (6 g),
1-bromoeicosane and 10 g potassium carbonate was refluxed in
acetone (70 ml) for 16 hours. The reaction mixture was poured into
water. The product was isolated by filtration, washed with water
and dried. Crystallisation from pentane yielded 7.2 g of
4-eicosanoxy-3,5-diphenylacetanilide as a white solid.
.sup.1H-NMR (CDCl.sub.3, selected data) .delta. 3.13(t, CH.sub.2O),
2.17 (s, Me).
Preparation of 4-eicosanoxy-3,5-diphenylaniline
##STR00004##
To 4-eicosanoxy-3,5-diphenylacetanilide (7.2 g) was added 24 g NaOH
in 30 ml H.sub.2O and 40 ml ethanol. The resulting mixture was
refluxed for 16 hours. The reaction mixture was poured on ice. The
product was isolated by filtration and washed with water.
Crystallisation from ethanol yielded 5.9 g (10.9 mmol) of
4-eicosanoxy-3,5-diphenylaniline as a white solid.
.sup.1H-NMR (CDCl.sub.3) .delta. 7.27-7.63 (m, 10H, ArH), 6.67 (s,
2H, ArH), 3.60 (br s, 2H, NH.sub.2), 3.09 (t, 2H, CH.sub.2O),
0.8-1.4 (m, 39H, alkyl).
Preparation of
2-[1-(2-t-butylphenylimino)ethyl]-6-[1-(4-eicosanoxy-3,5-diphenylphenylim-
ino)ethyl]pyridine (A)
##STR00005##
2-[1-(2-t-butylphenylimino)ethyl]-6-acetylpyridine (487 mg, 1.65
mmol), prepared according to the method described in US
2005/0059786, and 4-eicosanoxy-3,5-diphenylaniline (900 mg, 1.65
mmol) were dissolved in 50 ml of toluene. To this solution, 4 .ANG.
molecular sieves were added. After standing for 1 day the mixture
was filtered. The solvent was removed in vacuo. The residue was
crystallised from ethanol. The product A was isolated as an yellow
solid (600 mg, 0.73 mmol, 44%).
.sup.1H-NMR (CDCl.sub.3) .delta. 8.38 (dd, 2H, Py-H.sub.m), 7.90
(t, 1H, Py-H.sub.p), 6.5-7.7 (m, 16H, ArH), 3.21 (t, 2H,
CH.sub.2O), 2.52 (s, 3H, Me), 2.40 (s, 3H, Me), 1.37 (s, 9H, t-Bu),
0.8-1.35(m, 39H, alkyl).
Preparation of
2-[1-(2-t-butylphenylimino)ethyl]-6-[1-(4-eicosanoxy-3,5-diphenylphenylim-
ino)ethyl]pyridine cobalt[II] chloride complex, (B)
##STR00006##
In an inert atmosphere a solution of 300 mg (0.365 mmol) diimine A
in 10 ml dichloromethane was added to 40 mg CoCl.sub.2 (0.308 mmol)
in 5 ml dichloromethane. The mixture was stirred for 16 hours.
After filtration the solution was concentrated by removing part of
the solvent in vacuo. The product formed a jelly after addition of
10 ml pentane to the resulting solution (.about.2 ml). A yellowish
brown solid was isolated by centrifugation, washing with pentane
and drying in vacuo. Yield 234 mg (80%) of the cobalt complex
B.
.sup.1H-NMR(C.sub.6D.sub.6, broad signals, selected data) .delta.
113 (1H, Py-H.sub.m), 112 (1H, Py-H.sub.m), 18 (1H, Py-H.sub.p),
-10.8 (9H, t-Bu), -56.0 (2H, ArH), -85.6 (1H, ArH).
Preparation of a Cationic Catalyst Solution In Situ
In an inert atmosphere sodium
tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (ABCR GmbH & Co,
Karlsruhe, Germany) was added to a solution of an equimolar amount
of cobalt complex B in o-xylene. The solution was stirred for half
an hour at room temperature prior to injection in the autoclave.
The amount of cobalt complex B used is given below.
Alpha-Olefin Dimerizations in a 0.5-Liter Batch Autoclave
The dimerization experiments were performed in a 0.5 liter steel
autoclave equipped with jacket cooling with a heating/cooling bath
(ex. Julabo, model no. ATS-2) and a turbine/gas stirrer and
baffles. In order to avoid traces of water, the reactor was kept
under nitrogen pressure (0.5 MPa) at room temperature. Prior to the
experiment the reactor was scavenged by introducing 250 ml
o-xylene, MMAO (0.3 g solution in heptane) and subsequent stirring
at 70.degree. C. under nitrogen pressure of 0.5-0.6 MPa for 30 min.
The reactor contents were discharged via a tap in the base of the
autoclave. The reactor was evacuated to 0.4 kPa and cooled to
20.degree. C., after which it was loaded with 120 ml 1-butene
(grade 2.0, Hoek Loos) and the reactor was heated to 30.degree.
C.
Under stirring, the MMAO-solution (1207 micromoles) was then added
to the reactor with the aid of o-xylene (the MMAO-solution was
injected, the injector was subsequently rinsed twice) and the
stirring at 800 rpm was continued for 60 minutes.
The required amount (49 .mu.mol) of the cationic catalyst solution,
preparation of which is described above, was introduced into the
stirred reactor using an injection system, after which the injector
was rinsed three times with o-xylene. The total amount of o-xylene
introduced in the reactor was 13 ml.
The addition of the catalyst system resulted in a small exotherm
(generally 3-8.degree. C.), which was easily absorbed by the
thermostat bath, bringing the reactor back to the initial
conditions.
After about 3 hours, an aliquot of the reaction mixture was taken
for analyses and the reaction was allowed to continue for another
17 hours. After 20 hours and 40 minutes the experiment was stopped
by depressurising the autoclave and decanting under inert
atmosphere the product mixture into a collection bottle using a tap
in the base of the autoclave.
The amount and purity of C4, C8 and C12 olefins in the reaction
mixture was determined by gas chromatography after quenching the
sample with diluted sulphuric acid and using the introduced
o-xylene as internal standard. According to this method, 27.6 g of
a mixture of cis and trans 2-octene and 3-octene and 0.4 g of
C.sub.12 s were made. The ratio of the internal 2- and 3-octenes
over all octenes formed in the reaction was 98.4%. On the basis of
the GC data the turnover number to C.sub.8 s was 10,000 mol
1-butene/mol of Co. The percentage of 2-butene over
1-butene+2-butene in the C.sub.4 fraction was found to be
34.2%.
Analysis of the sample taken after 3 hours reaction time showed the
formation of 9.8 g of internal octenes with selectivity of 98.4%,
similar to the 20.5 hours sample. Turnover number was 3,550 mol
1-butene/mol of Co. The percentage of 2-butene over
1-butene+2-butene in the C.sub.4 fraction was found to be 8.6%.
The collected reaction mixture was transferred under inert
conditions to a distillation device and, still under inert
conditions the butenes present were slowly evaporated off at room
temperature. Subsequently, the remaining fraction was distilled at
room temperature under vacuum, the volatiles collected in two
fractions at low temperatures (-78.degree. C.), and stored under
inert conditions. Gas chromatography of the first fraction (5 ml)
showed it to be mainly heptane. Gas chromatography of the second
fraction showed it to consist of the C.sub.8 fraction, o-xylene,
and a small amount of heptane (solvent of MMAO). The C.sub.8
content of the second fraction was 75 w % with the same percentage
internal olefins as the original sample. This product was used in
the transmerization experiment described hereafter.
In a pressure vessel 4.0 g of olefin mixture described above (26.8
mmol) were weighed in under inert conditions together with 64 mg
n-hexadecane (internal standard), 0.5 g of
Al(n-C.sub.6H.sub.13).sub.3 (94.9% purity) and 215 mg of
Ni(COD).sub.2 dissolved in heptane (3 mg of Ni(COD).sub.2/g of
heptane amounting to 30 ppm Ni on total intake). The reaction
vessel was heated for 2 hours at 80.degree. C., subsequently cooled
to room temperature and the volatiles of the obtained reaction
mixture were distilled off at this temperature under vacuum. After
distillation 0.67 g of residue remained while 4.07 g volatiles were
collected as distillate. GC analysis of the distillate did not show
the presence of any n-hexadecane. A sample of 90 mg of the residue
was diluted in pentane, quenched with diluted sulphuric acid, and
the organic products analyzed by gas chromatography. GC showed the
presence of a C.sub.6 fraction consisting of n-hexane, of a C.sub.8
fraction consisting of n-octane, and some C.sub.12 impurities. On
the basis of the C.sub.6 and C.sub.8 data the formula of the
original Al compound can be calculated as
Al(C.sub.6H.sub.13).sub.0.76(C.sub.8H.sub.17).sub.2.24.
The residue obtained from the experiment described above, 0.58 g,
was reacted with 8.06 g (95.9 mmol) of 1-hexene in the presence of
88 mg Co naphthenate in nonane (1.2 mg of Co/g of nonane amounting
to 10 ppm Co on total intake). After stirring the reaction mixture
15 minutes at room temperature, a sample was taken, quenched with
acid, and the organic components analyzed by means of gas
chromatography. GC showed the presence of a C.sub.8 fraction
consisting of 93.1% 1-octene, 4.5% (n-octane+octene isomer), 2.2%
internal octenes, and 0.2% unidentified products. From the 4.5%
(n-octane+octene isomer) fraction at the most 0.6% is attributable
to the octene isomer. The total selectivity to linear octenes
defined as the selectivity to 1-octene+selectivity to n-octane is
97.0%.
GC analyses of a sample taken after 30 minutes of reaction showed
the same results.
This example shows that 1-butene can be converted to linear
1-octene using the process of the present invention with high yield
and high selectivity.
Instead of the trihexylaluminium, an equivalent amount of tri
n-butylaluminium may be used in step (b)(i) and a 10-fold molar
excess of 1-butene in the back displacement step (b)(ii) to
liberate 1-octene in high yield and selectivity.
The excess of 1-butene from step (b)(ii), which may contain a
little 2-butene can be recycled for reuse in step (b)(ii) and/or
recycled for reuse in the dimerization, optionally after
isomerization to an equilibrium mixture of 1-butene and 2-butene,
by heating at 120.degree. C. in the presence of a Na/K on alumina
catalyst under pressure.
Propene Conversion
This Example demonstrates the conversion of 1-propene to 1-hexene
using the process of the present invention.
The dimerization experiment was performed in a 0.5 liter steel
autoclave equipped with jacket cooling with a heating/cooling bath
(ex. Julabo, model no. ATS-2) and a turbine/gas stirrer and
baffles. In order to avoid traces of water, the reactor was kept
under nitrogen pressure (0.5 MPa) at room temperature. Prior to the
experiment the reactor was scavenged by introducing 250 ml toluene,
MAO (0.3 g solution in toluene) and subsequent stirring at
70.degree. C. under nitrogen pressure of 0.5-0.6 MPa for 30 min.
The reactor contents were discharged via a tap in the base of the
autoclave. The reactor was evacuated to 0.4 kPa and cooled to
20.degree. C., after which it was loaded with 51 g propene (grade
2.5, Hoek Loos N.V.) and 160 ml toluene. The reactor was
subsequently heated to 50.degree. C. giving a pressure of 8.4
barg.
Under stirring, the MAO-solution (4 mmol) was then added to the
reactor with the aid of toluene (the MAO-solution was injected, the
injector was subsequently rinsed twice) and the stirring at 800 rpm
was continued for 30 minutes.
The required amount (40 .mu.mol) of the cationic catalyst solution,
preparation of which is described above with the only difference
that toluene was used as the solvent instead of o-xylene, was
introduced into the stirred reactor using an injection system,
after which the injector was rinsed three times with toluene. The
total amount of toluene introduced in the reactor was 200 ml.
The addition of the catalyst system resulted in a small exotherm
(generally 2-7.degree. C.), which was easily absorbed by the
thermostat bath, bringing the reactor back to the initial
conditions.
After 14 minutes a weighed amount of hexylbenzene (1 g) was
injected into the reactor to serve as internal standard for GC
analysis. Directly afterwards (after 16 minutes) the experiment was
stopped by depressurising the autoclave and decanting under inert
atmosphere the product mixture into a collection bottle, containing
diluted sulphuric acid (to deactivate the catalyst), using a tap in
the base of the autoclave.
The amount and purity of C6, C9 and C12 olefins in the reaction
mixture were determined by gas chromatography using the introduced
hexylbenzene as internal standard. According to this method, 9.8 g
of C.sub.6 s, 1.0 g of C.sub.9 s and 0.07 g of C.sub.12 s were
made. In the C.sub.6 fraction the ratio of 1-hexene to cis/trans
2-hexene was 39:60. The ratio of the linear hexenes over all
hexenes formed in the reaction was 98.9%. On the basis of the GC
data the turnover number to propene oligomers was 11,600 mol
propene/mol of Co. The conversion of propene was found to be
21.4%.
After removal of propene, the solvent, hexylbenzene and the higher
oligomers of propene by vacuum distillation under inert conditions
the 1+2-hexene mixture may be used in a transmerization experiment
to be carried out analogous to the above-described transmerization
experiment with internal octenes, but now using trioctylaluminium
instead of trihexylaluminium in the transmerization step (b)(i) and
using 1-octene instead of 1-hexene in the final back displacement
step (b)(ii).
The transmerization step (b)(i) may be performed as generally
described according to the procedure of Ex 14A of U.S. Pat. No.
5,124,465 with an equivalent amount of trioctyl-aluminium instead
of tripropylaluminium. The back displacement step (b)(ii) may be
performed as generally described according to the procedure of Ex
14 B of EP 505834A with 1-octene. A high yield and selectivity of
formation of 1-hexene may be obtained.
Instead of the trioctylaluminium, an equivalent amount of
tri-n-propylaluminium may be used in step (b)(i) and, instead of
1-octene a 10 fold molar excess of propylene may be used in the
back displacement step (b)(ii). The excess of propylene from step
(b)(ii) can be recycled for reuse in step (b)(ii) and/or recycled
for reuse in the dimerization.
* * * * *